1. Field of the Invention
The invention relates to a yarn guide rod for a machine that produces cross-wound bobbins or cheeses, which includes axially coupled-together partial rods being formed essentially of fibers embedded in a plastic matrix.
Machines that produce cross-wound bobbins or cheeses, such as open-end spinning machines, are relatively long (20 to 30 meters, for instance) and have many production stations for cheeses located next to one another. In such machines, yarn guide rods are used to control the reciprocating yarn guides of one entire side of the machine. That kind of yarn guide rod must accordingly have a corresponding length. Like the machine units disposed next to one another and mounted to one another at a setup site, it is therefore fabricated in individual rod segments, which are coupled together upon installation. The rod connection of the partial rods must be firm and immune to vibration, they must remain dimensionally stable over a high number of hours in operation, yet they must be separable.
One such rod connection, that is referred to therein as a gripping fist, has been disclosed by German Published, Non-Prosecuted Application DE 38 12 493 A1. The partial rods to be joined therein are formed of steel tubes having ends with inlays for reinforcement in the region of the connecting elements.
The tubular yarn guide rods that are coupled together from partial rods, with their considerable length as mentioned above, are strained, for instance with a stroke of 150 to 300 mm and a yarn guide frequency of 1 to 8 Hz. If the natural frequency is inadequately far from the yarn guide frequency, then the resonant behavior of such a yarn guide bar is unfavorable. In other words, resonance step-ups and therefore malfunctions can occur. Above all, an additional longitudinal vibration is superimposed on the actual stroke of the yarn guide rod from stretching or elongation at the stroke turning point. This additional vibration may have an amplitude of several millimeters at the end of the yarn guide rod opposite the drive mechanism. The result is wider bobbins with poorer yarn winding on that end of the machine.
In order to counteract that problem, it has already been proposed in German Published, Non-Prosecuted Application DE 34 34 027 A1 that the yarn guide rod be fabricated from multiply-vaned profile rods with a star-shaped or radial profile, which are made of artificial-resin-reinforced fibers, that is fibers embedded in a plastic matrix. The profile described therein is supposed to be constructed in such a way that ceramic parts, for instance, can be clipped in place and at the same time adhesively bonded between the profile vanes that extend longitudinally of the yarn guide rod. Those ceramic parts should in turn form the slide partner for slide bearings with which the yarn guide rod is guided. Moreover, such connecting parts are intended to serve as mounts for the actual yarn guides. Other parts that are secured in the same way are intended to perform the function of rod connectors. Finally, the profile structure is intended to make it possible to catch abrasion from the profile material, in order to prevent abraded material from being entrained by the traveling yarn and wound up.
The above-described construction is relatively complicated. Moreover, the clipping and adhesive bonding connections cannot withstand the heavy strains during operation, over the long term.